The generation now entering the work force, people in their late teens and early 20s, are consistently panned by many employers as not ready for the workplace. But while there are real differences, their behavior on the job might not be so different from that of previous generations.

In surveys, middle-aged business owners and hiring managers say the new workers lack the attitudes and behaviors needed for job success. They don’t have a strong work ethic, these reports say. They’re not motivated and don’t take the initiative. They’re undependable and not committed to their employers. They need constant affirmation and expect rapid advancement.

A recent report by Bentley University for example, found more than half of corporate recruiters rated recent college graduates with a grade of C or lower for preparedness; nearly seven in 10 said young workers were difficult for their organization to manage. The Pew Research Center found that more than half of college presidents thought today’s students were less prepared, and studied less, than students did a decade ago.

But complaining about youth on the cusp of adulthood isn’t novel. Back in the Middle Ages, masters complained about their apprentices’ work habits.

"You can find these complaints in ancient Greek literature, in the Bible,” said Peter Cappelli, director of the Center for Human Resources at the Wharton School. "It reflects the way old people see young people."

Professor Cappelli said that young peoples’ attitudes toward work and career had not changed significantly since the baby boomers came of age in the 1960s. There’s no evidence millennials are different," he said. "They’re just younger."

Adam Tratt, 42, manages several employees in their 20s. From an employment standpoint, he and his friends looked a bit aimless at that age too, he said.

"I remember very explicitly when I was graduating from college, this stereotype of Gen-Xers as slackers," he said, referring to those born between roughly 1965 and 1982, and who are now in their mid-30s and 40s. Mr. Tratt, who runs a software start-up in Seattle, said his generation gained a reputation in middle age as entrepreneurial and hard-working.

Professor Cappelli challenged middle-aged managers to remember when they were 22. "You probably wanted to get out of the office in a hurry — you were interested in what was going on after work," he said. "You had these bursts of energy and great enthusiasm about something, but you also didn’t have a lot of resilience."

Many people who supervise young workers, though, do echo the prevailing view that millennials have some troublesome work habits.

Robert Boggs is an administrator at Corinthian Colleges in Southern California and has managed several people under 30 on his staff. "They tend to be very self-absorbed; they value fun in their personal and their work life," said Mr. Boggs. "Because they’ve grown up multitasking on their mobile, iPad and computer, I can’t expect them to work on one project for any amount of time without getting bored."

Thomas Gallagher has hired several young athletes over the years in his sporting equipment business in Wilmington, Del. He says he thinks many young workers lack perseverance. "I worry that if I give someone a long-term task, if things don’t work out in the short term, I’m going to get an email or phone call saying, 'You know what? This isn’t for me. I give up, I can’t do this,'" Mr. Gallagher said.

Some of these negative views are even shared by many in the generation in question.

"I see a lot of students cheating their way through, just sliding by," said Claire Koerner, 21, a student at the University of Washington in Seattle.

Ms. Koerner is finishing a B.A. in business administration while working at a wedding-planning start-up, OneWed. She does social media for the company while in class, she admitted. But she said many of her peers had not held a job at all. (According to the federal Bureau of Labor Statistics, teenage labor force participation is at record lows.) "They just aren’t going to have the skills to work as hard as they’re expected to," she said.

Camille Perry, 26, of Portland, Ore., said her generation had a poor work ethic, although her own schedule was filled with labor. She holds two jobs: bartending at a neighborhood karaoke lounge and serving at a downtown lunch restaurant.

"We are a generation that spent a lot of time in front of the television or playing video games," she said. "There’s just a prevalent laziness."

Academics who study this generation said its members did differ from Generation X and baby boomers, those born from 1946 to 1964, and the differences may persist through their work lives.

"This is the most affirmed generation in history," said Cliff Zukin, a senior research fellow at the Heldrich Center for Workforce Development at Rutgers University, where he is also a professor of public policy. "They were raised believing they could do whatever they wanted to, that they have skills and talents to bring to a job setting.

"And when they’re lucky enough to get a job they’re basically told, ‘Be quiet, you don’t really know anything yet.’ For a lot of them, this is a tremendous clash between their expectations and the reality of the job."

The generation may be shaped more by the Great Recession than by their overprotected, tech-saturated upbringing. If they lack the loyalty and commitment that employers want in entry-level workers, is that really such a surprise?

"I think it has less to do with lack of conscientiousness — it’s more a recognition that no company is going to bury you when you die," said Scott Ruthfield, 39, who runs Rooster Park, a recruitment firm in Seattle. "You’ve seen your parents go through large companies that don’t take care of them, and you realize that you’re responsible for your own well-being."

In a potential plus for employers, young people have learned — at home, at school, through their shared online networks — to value collaboration and teamwork over competition, so everyone can win, said Paul Taylor, executive vice president of special projects at the Pew Research Center.

"They are a generation that is not conflictual," Mr. Taylor said. "They don’t want to get into fights. That augers well for their ability to adapt and get along in a workplace."

Work in America: Our special series in partnership with the New York Times looking at how the improvements in technology, combined with companies’ increased ability to outsource, have conspired to make radical changes to work in America.

Young people’s multitasking on mobile devices might seem like a distraction at work, but it also has an upside.

John Scrofano, 31, who is Ms. Koerner’s boss at OneWed in Seattle, appreciates the comfort his younger employees have with social media. "They don’t have that line between work and home that used to exist, so they’re doing Facebook for the company at night, on Saturday or Sunday," he said. "We get incredible productivity out of them."